Which fault is most likely if the lead pump amperage is lower than normal and the water level continues to rise after startup?

Which fault is most likely if the lead pump amperage is lower than normal and the water level continues to rise after startup?

• A. Lag pump is air-bound
• B. Lag pump is closed
• C. Force main pressure too high
• D. Lead pump is air-bound

Answer: (D)

Leading pump air-bound is the most likely fault. When air is trapped in the suction line or inside the pump, the impeller can’t move water, so the pump runs with very little load. That means the motor draws less current than normal, so amperage drops. At the same time, because the pump isn’t moving water out of the basin, the water level keeps rising after startup. This combination—low amperage and rising water level—points to an air-bound condition on the lead pump. The other faults wouldn’t typically produce both symptoms together: for example, an air-bound lag pump wouldn’t cause the lead to show low amperage, a force-main pressure issue would usually increase load (and amperage), and a truly closed lead pump would prevent startup or show different current behavior.

Leading pump air-bound is the most likely fault. When air is trapped in the suction line or inside the pump, the impeller can’t move water, so the pump runs with very little load. That means the motor draws less current than normal, so amperage drops. At the same time, because the pump isn’t moving water out of the basin, the water level keeps rising after startup. This combination—low amperage and rising water level—points to an air-bound condition on the lead pump. The other faults wouldn’t typically produce both symptoms together: for example, an air-bound lag pump wouldn’t cause the lead to show low amperage, a force-main pressure issue would usually increase load (and amperage), and a truly closed lead pump would prevent startup or show different current behavior.